PMI Sequence Explorer

Propagation Monotone Increasing (PMI) sequences arise in zero forcing on grid graphs. When a zero forcing propagation is run on an n×m grid, the order in which vertices turn blue forms a propagation sequence. This sequence is called 2D-monotone (or PMI) if the row indices of the forced vertices are non-decreasing throughout the sequence. Use this explorer to select an initial blue set, simulate propagation, and inspect whether the resulting sequence satisfies the PMI property — step by step.

Grid Graph — click vertices to select initial blue set

Propagation Sequence

Select vertices and click Simulate.

Step-by-Step Table

Step	Vertex (row, col)	Row index	Col index	PMI ✓/✗

PMI checks that each row index ≥ previous row index. Initial vertices shown in blue.